5 files changed, 56 insertions, 3 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 5c7325c5c5e6..6fa01aea2488 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -685,7 +685,10 @@ static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync)
 	if (ctx->cred != NULL)
 		put_rpccred(ctx->cred);
 	dput(ctx->dentry);
-	nfs_sb_deactive(sb);
+	if (is_sync)
+		nfs_sb_deactive(sb);
+	else
+		nfs_sb_deactive_async(sb);
 	kfree(ctx->mdsthreshold);
 	kfree(ctx);
 }
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index a54fe51c1dfb..05521cadac2e 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -351,6 +351,7 @@ extern int __init register_nfs_fs(void);
 extern void __exit unregister_nfs_fs(void);
 extern void nfs_sb_active(struct super_block *sb);
 extern void nfs_sb_deactive(struct super_block *sb);
+extern void nfs_sb_deactive_async(struct super_block *sb);
 
 /* namespace.c */
 #define NFS_PATH_CANONICAL 1
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 1465364501ba..8cfbac1a8d5e 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2197,7 +2197,7 @@ static void nfs4_free_closedata(void *data)
 	nfs4_put_open_state(calldata->state);
 	nfs_free_seqid(calldata->arg.seqid);
 	nfs4_put_state_owner(sp);
-	nfs_sb_deactive(sb);
+	nfs_sb_deactive_async(sb);
 	kfree(calldata);
 }
 
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 13c2a5be4765..652d3f7176a9 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -54,6 +54,7 @@
 #include <linux/parser.h>
 #include <linux/nsproxy.h>
 #include <linux/rcupdate.h>
+#include <linux/kthread.h>
 
 #include <asm/uaccess.h>
 
@@ -415,6 +416,54 @@ void nfs_sb_deactive(struct super_block *sb)
 }
 EXPORT_SYMBOL_GPL(nfs_sb_deactive);
 
+static int nfs_deactivate_super_async_work(void *ptr)
+{
+	struct super_block *sb = ptr;
+
+	deactivate_super(sb);
+	module_put_and_exit(0);
+	return 0;
+}
+
+/*
+ * same effect as deactivate_super, but will do final unmount in kthread
+ * context
+ */
+static void nfs_deactivate_super_async(struct super_block *sb)
+{
+	struct task_struct *task;
+	char buf[INET6_ADDRSTRLEN + 1];
+	struct nfs_server *server = NFS_SB(sb);
+	struct nfs_client *clp = server->nfs_client;
+
+	if (!atomic_add_unless(&sb->s_active, -1, 1)) {
+		rcu_read_lock();
+		snprintf(buf, sizeof(buf),
+			rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));
+		rcu_read_unlock();
+
+		__module_get(THIS_MODULE);
+		task = kthread_run(nfs_deactivate_super_async_work, sb,
+				"%s-deactivate-super", buf);
+		if (IS_ERR(task)) {
+			pr_err("%s: kthread_run: %ld\n",
+				__func__, PTR_ERR(task));
+			/* make synchronous call and hope for the best */
+			deactivate_super(sb);
+			module_put(THIS_MODULE);
+		}
+	}
+}
+
+void nfs_sb_deactive_async(struct super_block *sb)
+{
+	struct nfs_server *server = NFS_SB(sb);
+
+	if (atomic_dec_and_test(&server->active))
+		nfs_deactivate_super_async(sb);
+}
+EXPORT_SYMBOL_GPL(nfs_sb_deactive_async);
+
 /*
  * Deliver file system statistics to userspace
  */
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index 13cea637eff8..3f79c77153b8 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -95,7 +95,7 @@ static void nfs_async_unlink_release(void *calldata)
 
 	nfs_dec_sillycount(data->dir);
 	nfs_free_unlinkdata(data);
-	nfs_sb_deactive(sb);
+	nfs_sb_deactive_async(sb);
 }
 
 static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)